American pharmaceutical giant Pfizer announced Monday that it will acquire the California-based Anacor Pharmaceuticals in a deal valued at $5.2 billion. Pfizer will shell out $99.25 per share of Anacor as part of the transaction that was approved unanimously by the board of directors of both companies.

This represents a 55 percent premium over Anacor stock’s closing price Friday.

“We believe the acquisition of Anacor represents an attractive opportunity to address a significant unmet medical need for a large patient population with mild-to-moderate atopic dermatitis, which currently has few safe topical treatments available,” Albert Bourla, president of Pfizer’s global innovative pharma and global vaccines, oncology and consumer healthcare businesses, said in a statement.

Anacor’s flagship asset is Crisaborole — a non-steroidal gel for the treatment of eczema.

“If approved, Pfizer believes peak year sales for crisaborole have the potential to reach or exceed $2.0 billion,” the two companies said in the joint statement.

Earlier this month, Pfizer, which recently scrapped its $160 billion merger with Ireland-based Allergan — after the U.S. treasury department imposed tough restrictions on so-called corporate tax inversions — reported earnings of 67 cents a share in the first quarter of 2016, topping analysts' estimates of 55 cents a share. Revenue for the three-month period ending March 31, boosted by its cancer drug sales and its acquisition of Hospira in September, also beat estimates, coming in at $13.01 billion — a jump of 20 percent over the figure of $18.86 billion in the previous year.

On Monday, shares of Anacor, which has a market cap of $3 billion, surged over 53 percent in pre-market trade. Pfizer’s shares, meanwhile, were unchanged.